The width of a conventional self-tapping screw head is usually wider than that of a screw rod, and forms a shape similar to a funnel. Thus, when the screw is fastened into an object, the screw head is pressed tightly against a drill hole to achieve a tight binding effect. However, for wood having high rigidity, rotating the screw thereinto can be effort-consuming, and wood crumbs produced during the process of rotating the screw cannot be effectively discharged. As a result, compression is caused when the residual wood crumbs in the wood receive the force from the screw being rotated into the wood, easily causing cracking and damaging of the wood.
For example, the Taiwan Patent No. I496997 provides a screw capable of accommodating wood crumbs. A plurality of outwardly protruding auxiliary blocks are provided on a lower surface of a screw head, and an accommodating region is formed between two adjacent of the auxiliary blocks. Each of the auxiliary blocks has one wall surface located at one side of the accommodating region and extending upwards from the lower surface, an upholding wall formed by the other side of the wall surface connecting towards another adjacent accommodating region, and a cutting blade formed and connected at the wall surface and the upholding wall. The fastening member can be cut when fastening and entering a fastened object, and crumbs can be accommodated in the accommodating regions, generating effectiveness of tight binding. However, in an actual application of the above screw, issues of expanded edges of an object and cracking open of screw holes are easily resulted. Therefore, there is a need for a solution that resolves issues of the prior art.